CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Patent Application

Serial No. 62/971,340, filed on February 7, 2020, and entitled “START OF PUMPING SENSOR,” the complete disclosure of which is expressly incorporated by reference herein.

TECHNICAL FIELD OF THE DISCLOSURE

[0002] The present disclosure relates to a start of pumping (SOP) sensor, and more specifically, to placement of a SOP sensor within a fueling system.

BACKGROUND OF THE DISCLOSURE

[0003] In internal combustion engines, one or more fuel pumps deliver fuel to a fuel accumulator. Fuel is delivered by fuel injectors from the accumulator to cylinders of the engine for combustion to power operation of the system driven by the engine. It is desirable for a variety of reasons to accurately characterize the amount of fuel delivered by the fuel pump to the accumulator to use for diagnostics and fuel quantity corrections. In conventional fuel delivery systems, a pressure and/or temperature sensor is positioned within a fuel rail. However, this type of sensor placement fails to capture transient dynamics of the fuel delivery system. Thus, a fuel system is needed with improved sensor placement for capturing transient dynamics of the fuel delivery system.

SUMMARY OF THE DISCLOSURE

[0004] In one embodiment of the present disclosure, a fueling system is disclosed. The fueling system comprises a high pressure fuel pump including a barrel having a fuel inlet and a fuel outlet, a fuel rail positioned downstream of the high pressure fuel pump, a fuel outlet line coupling the high pressure fuel pump to the fuel rail, an outlet check valve positioned along the fuel outlet line upstream of the fuel rail, and at least one sensor configured to measure at least one of pressure and temperature of fuel within the fueling system, wherein the at least one sensor is one of directly coupled to the barrel or coupled to the fuel outlet line upstream of the fuel rail BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Advantages and features of the embodiments of this disclosure will become more apparent from the following detailed description of exemplary embodiments when viewed in conjunction with the accompanying drawings, wherein:

[0006] FIG. 1 shows a schematic diagram of a fueling system with an SOP sensor in a first position for improved readings;

[0007] FIG. 2 shows a schematic diagram of the fueling system of FIG. 1 with the SOP sensor in a second position for improved readings; and

[0008] FIG. 3 shows a schematic diagram of the fueling system of FIG. 1 with the SOP sensor in a third position for improved readings.

[0009] Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present disclosure, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present disclosure. The exemplifications set out herein illustrate embodiments of the disclosure, in one form, and such exemplifications are not to be construed as limiting the scope of the disclosure in any manner.

DETAILED DESCRIPTION OF THE DRAWINGS [0010] Referring now to FIGS. 1-3, a schematic diagram of a portion of a fueling system

100 is shown. Fueling system 100 comprises a high pressure fuel pump 10, which includes a plunger 12 that reciprocates within a barrel 14 as is known in the art. Fuel is supplied to a chamber 16 within barrel 14 through an inlet 18, compressed by upward motion of plunger 12 such that the pressure of the fuel is increased, and supplied through an outlet 20 to an outlet line 19, through an outlet check valve (OCV) 22, and to a fuel reservoir, such as a common rail accumulator (hereinafter, rail 24). Fuel from rail 24 is periodically delivered by a plurality of fuel injectors 25 to a corresponding plurality of cylinders (not shown) of an internal combustion engine (not shown). A small circumferential gap 26 exists between an outer surface 28 of plunger 12 and an inner surface 30 of barrel 14 to permit reciprocal motion of plunger 12 within barrel 14. During the pumping operation of pump 10, fuel can only flow as supply fuel through outlet 20, outlet line 19, and OCV 22 to rail 24 and/or as leakage through gap 26 to a return line 32. [0011] As plunger 12 moves through the pumping cycle, it moves between a start-of- pumping (SOP) position and an end-of-pumping (EOP) position. The SOP position is after plunger 12 moves through its bottom-dead-center (BDC) position and the EOP position precedes the top- dead-center (TDC) position of plunger 12.

[0012] As indicated above, during the compression stroke of plunger 12 (i.e., as it moves from the BDC position to the TDC position), fuel in chamber 16 is compressed, causing the pressure in chamber 16 to increase to a point where the force on the chamber side of OCV 22 is equal to the force on the rail side of OCV 22. As a result, OCV 22 opens and fuel begins to flow through outlet 20, outlet line 19, and OCV 22 to rail 24. This initial opening of OCV 22 and flow of fuel through outlet 20 is known as the start of pumping or SOP, and occurs when plunger 12 is at the SOP position. Fuel continues to flow in this manner to rail 24 as plunger 12 continues to travel toward the TDC position. Consequently, the pressure of fuel in rail 24 increases. Once the desired amount of fuel is passed from pump 10 to rail 24, OCV 22 closes and fuel no longer flows through outlet 20. This ceasing of fuel flow is known as the end of pumping or EOP, and occurs when plunger 12 is at the EOP position. However, based on the various diagnostics and/or performance of fueling system 100, the SOP position may need to shift to continue to properly supply the desired amount of fuel to rail 24. In various embodiments, the EOP position may also or alternatively need to be shifted, for instance, when pump 10 changes sync relative to the engine. [0013] A processor 21 receives measurements of the pressure of fuel and/or the temperature of fuel within system 100 from a pressure/temperature sensor 23. Processor 21 also controls operation of injectors 25 as described herein. In previous fueling systems, a pressure/temperature sensor(s) is positioned on rail 24 to receive pressure/temperature readings within rail 24. However, in the present disclosure, pressure/temperature sensor 23 is positioned adjacent to or coupled directly to barrel 14 of pump 10 before rail 24 and OCV 22 or positioned along outlet line 19 upstream of rail 24 but downstream of OCV 22. In various embodiments, sensor 23 is positioned within an opening 34 or 20 in barrel 14 of pump 10 (FIG. 1), while in other various embodiments, sensor 23 is positioned along outlet line 19 upstream of rail 24 (FIGS. 2 and 3). When sensor 23 is positioned adjacent pump 10 along outlet line 19, a plug 36 may be positioned within opening 34 or 20 of barrel 14. In various embodiments, outlet line 19 may be coupled to barrel 14 at opening 34, while sensor 23 is placed within outlet 20, while in other various embodiments, outlet line 19 may be coupled to barrel 14 at outlet 20, while sensor 23 is placed within opening 34.

[0014] Sensor 23 may be the sole pressure and/or temperature sensor in fueling system

100, or sensor 23 may be an additional sensor provided to fueling system 100 in addition to a sensor traditionally provided on rail 24. In either configuration, the pressure and/or temperature readings provided by sensor 23 may be used in various algorithms to allow performance and diagnostics of fueling system 100 to be determined. For instance, readings from sensor 23 may be used to estimate the start of pumping (i.e., the time at which the transfer of mass to rail 24 is begun), end of pumping or pump sync (i.e., the time at which the transfer of mass to rail 24 ends), fuel density, and/or barrel -plunger leakage (i.e., the flow that escapes pumping chamber 16 between plunger 12 and barrel 26 through gap 26 to return line 32 as the fuel is being compressed). These various algorithms may include those disclosed in PCT International Patent Application No. PCT/US2018/026891, filed on April 10, 2018, and entitled “ADAPTIVE HIGH PRESSURE FUEL PUMP SYSTEM AND METHOD FOR PREDICTING PUMPED MASS” (Attorney Docket No. Cl- 17-0699-01 -WO), and/or PCT International Patent Application No. PCT/US2018/026874, filed on April 10, 2018, and entitled “SYSTEM AND METHOD FOR MEASURING FUEL INJECTION DURING PUMP OPERATION” (Attorney Docket No. Cl- 17- 0697-01 -WO), the complete disclosures of which are expressly incorporated by reference herein. When sensor 23 is provided in addition to another sensor, rationality diagnostics may be implemented to further improve diagnostic estimations.

[0015] Providing sensor 23 closer to pump 10 provides various benefits. For example, the placement of sensor 23 closer to pump 10 gives a more distinct pressure transient and/or response when fuel is being pumped from pump 10 to rail 24 as compared to a sensor placed within rail 24. In addition, the placement of sensor 23 also allows for improved temperature readings. Temperature readings for fueling system 100 are typically measured by a thermocouple integrated into sensor 23. The fuel temperature is estimated within the pressurized volume by measuring the temperature of the structure which sensor 23 is coupled, which according to the present disclosure would be barrel 14 or outlet line 19. Improved temperature measurements in the transient conditions may be provided when sensor 23 is coupled along outlet line 19 due to the increased flow velocity caused by outlet line 19 having a smaller diameter and/or area than rail 24 which results in a relatively high heat transfer coefficient between the fuel and outlet line 19, and a reduced wall thickness, which leads to a relatively low thermal mass. These benefits allow for improved estimates of the start of pumping (SOP), which in turn allows for better estimates of the end of pumping (EOP), fuel density and/or the barrel- plunger leakage using the estimated SOP.

[0016] EOP is the point at which pump 10 stops providing fuel to outlet line 19, or when the cam of pump 10 reaches its highest position. EOP may be used to see how pump 10 is synced with the engine (not shown). Knowing EOP is useful for various diagnostics. For instance, by knowing where EOP is and where SOP is, a pumping duration can be calculated, and using the pumping duration and knowledge of geometry of the cam profile, a volume of fuel pumped can be calculated. From the volume of fuel pumped and the increase in pressure determined from sensor 23, the fuel density can be estimated.

[0017] Improved estimates of SOP also allow for barrel -plunger leakage to be better estimated. Barrel -plunger leakage relates to the fuel that escapes from chamber 16 and goes into drain circuit 32 back to the fuel tank. This leakage varies with pressure and/or duration of pumping. For instance, if pressure within chamber 16 is high and duration of pumping is long, the leakage is often more than when pressure within chamber 16 is low and duration of pumping is short or when pressure within chamber 16 is high and duration of pumping is short or pressure within chamber 16 is low and duration of pumping is long. More leakage means pump 10 must start delivering fuel earlier to deliver the same quantity, and therefore results in an adjusted SOP. An adjusted SOP due to engine speed and/or pressure changes results in a different amount of leakage which can be determined from the adjusted SOP which may be estimated using sensor 23.

[0018] By providing improved estimates, the algorithm(s) and system as a whole can use active inlet metering (AIM), or inlet check valves active in metering how much fuel is pumped, to determine the valve closing delay or the delay between a valve closing command and actual closing of the valve. Determining the valve closing delay allows for improved system performance in that the SOP position may be adjusted to take the valve closing delay into consideration for more precise fuel delivery. A pumping event for the valve typically has 5 phases: current is sent to the valve actuator, the valve starts to move, the valve reaches its end position, sealing the pump chamber, the fuel is compressed until the point when the pressure exceeds the rail pressure, and the OCV opens (i.e., SOP) and mass is transferred to the rail. Knowing when the current was commanded to go high, the compressibility of the fuel, the geometrical dimensions of the pump cam and the plunger, and the estimated SOP, it is possible to estimate the closing delay (i.e., the duration from current going high to when the valve closes). This delay can then in turn be used to provide more precise fuel delivery.

[0019] While various embodiments of the disclosure have been shown and described, it is understood that these embodiments are not limited thereto. The embodiments may be changed, modified and further applied by those skilled in the art. Therefore, these embodiments are not limited to the detail shown and described previously, but also include all such changes and modifications.

[0020] Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements. The scope is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B or C may be present in a single embodiment; for example, A and B, A and C,

B and C, or A and B and C.

[0021] In the detailed description herein, references to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art with the benefit of the present disclosure to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.

[0022] Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. § 112(f), unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.